Generation of CD8 T cell memory critically contributes to the control of intracellular pathogens and tumors. Yet how memory T cells are generated is unclear. Signals derived from the recognition of antigen by T cell receptors (TCR) and inflammation initiate the programming of memory T cells. T-bet and Eomes are two transcription factors key in this process. Thus, as T cells progressively differentiate into memory cells, low levels of T bet and increasing levels of Eomes seem to confer memory cells with the ability to live long and vigorously expand in secondary infections. While it is known that inflammation affects both T-bet and Eomes levels, it is still unclear how antigenic signals contribute to govern these regulators of memory. Our long-term goal is to understand how TCR signals regulate memory development. Our preliminary data suggest that (1) TCR signals utilize the NFkB pathway to regulate Eomes expression and thereby, memory. (2) TCR proximal events that regulate the NFkB-Eomes-memory axis are different depending on TCR signal strength. Therefore, our central hypothesis is that TCR-dependent NFkB signals regulate Eomes expression and T cell memory development. We have generated a unique murine model where a point mutation in the TCR is able to uncouple memory differentiation from effector development and proliferation in response to strong but not weak antigenic signals. We will use this model and two new mouse models that allow for T-cell restricted conditional inhibition or enhancement of NFkB signals to test our hypothesis. In this proposal we plan to determine when and how NFkB signals regulate CD8 memory (Aim 1) and to delineate the TCR-proximal signaling events required for Eomes expression and memory under both strong and weak TCR stimulation (Aim 2). This approach is innovative because it will combine studies in novel and unique murine models that for the first time directly connect TCR signals and memory development and systems that regulate the TCR-dependent and independent activity of the NFkB pathway in sophisticated adoptive transfer experiments. The proposed research is significant since it will increase our knowledge of the signaling pathways that regulate memory differentiation and it will provide an unprecedented mechanistic insight into how strong/foreign antigenic signals and weak/self-peptide signals regulate memory programming. We anticipate that the studies in this proposal will aid in the design of new therapeutic strategies to improve vaccines and tumor therapies.